|Couch's Spadefoot Photo by Rick Halliburton|
A chorus of toads may include up to five species in our area, each adding their own rhythm and pitch to the performance. All of the choristers are male, ardently singing to attract mates. Couch's spadefoots bleat like lambs. Red-spotted toads trill. The Sonoran Desert toad adds a loud intermittent "Squawk!" and Great Plain's toads will chime in with a persistent jackhammer backbeat. If Woodhouse's toads are about, they'll croon a loud "Waaaaaah!"
Of these, Couch's spadefoots are the most common in the suburbs of Phoenix during monsoon season. Spadefoots, named for the tiny digging tools on the bottoms of their hind feet, are cued to emerge not by moisture, but by staccato drumbeats of hard rain and vibrations of thunder. The opportunity to mate is the primary motivation for toads to wake up from nearly a year of dormancy buried in the earth up to three feet below the surface. Eating comes second.
At this end of the Valley, Skunk Creek, New River, and Cave Creek are excellent venues for toad concerts. "Creek" and "river" are deceptive names for these usually dry washes that may only flow for a few days a year. But an inch of rain anywhere upstream in the watershed can transform a wash to a raging torrent in a matter of hours. When the floods settle down, the pools left behind become toad nurseries.
Spadefoots are famous for being one of the most rapidly developing amphibians in the world. One lady Couch's spadefoot can produce over 3,000 eggs that will hatch within a day of being fertilized. Then the race is on for tadpoles to develop into toadlets before the pond evaporates. If they don't get eaten, they can hop out of the pond within eight days. After surviving that challenge, a toadlet must then navigate the world of terrestrial predators, which includes lizards, snakes, raccoons, birds, other toads, and even spiders. Of thousands of eggs, perhaps one percent will live the two years it takes to become a breeding adult. These lucky survivors may live up to ten or more years in the wild.
Many amphibian species around the world are suffering severe population losses due to a suite of factors, including habitat destruction, fungi and water pollution. "Toads that are adapted to temporary ponds in the Sonoran desert seem oblivious to these threats," notes herpetologist Brian Sullivan, a professor at ASU. He's been studying populations along Skunk Creek and Cave Creek for over three decades and sees no sign of decline. "There is, however, plenty of variation between years, as is expected in a climate like ours," he explains. "Successful breeding happens about one in five years, which is about how often the monsoon pools will last long enough for tadpoles to develop into toadlets."
Even with the abuses of road construction, flood control dams and off-road vehicle recreation, some of the washes in suburban areas remain excellent habitat for toads. "There is always something fascinating going on in suburban desert washes," Say Randy Babb, herpetologist at the Arizona Game and Fish Department. For Babb, toad season is a favorite time of year. "I highly recommend that folks turn of the TV, abandon your computer, and get out to witness one of nature's coolest miracles," exclaims Babb.
Tickets are free!
If you’d like to identify toad songs you hear at your next toad concert, log onto the Reptiles and Amphibians of Arizona website to hear recordings: http://www.reptilesofaz.org/index.html
Arizona Game & Fish Department also has some excellent videos of local toads at their website: http://www.azgfd.gov/video/AmphibiansofArizona.shtml
Warning: Handling any toad may cause an allergic or toxic reaction in most people as well as dogs who try to eat them. Neurotoxins are secreted from a toad’s parotoid glands, a pair of lumps behind their eyes. However, you do not have to worry about getting warts from handling toads.